let's talk about polygons what is a polygon a polygon is a category of shapes there are many different types of polygons just like there are many different types of dogs a German Shepherd is a type of dog a rectangle is a type of polygon what does it take to be a dog dogs have four legs they have fur and they have sharp teeth what does it take to be a polygon it has to be a closed figure with straight sides and it needs at least three sides what is a closed figure this rectangle is a closed figure because it doesn't have any openings you can think about pouring liquid into this shape you wouldn't be able to pour any liquid into this rectangle because it's closed this one is open it's missing one side and you would be able to pour liquid right into it like a glass or a cup what are straight sides well this shape has straight sides This shape has a curved side one of its sides is straight but the other is curved and rounded like a circle this shape is a polygon because it has straight sides that one is not because one of its sides is curved what does three or more sides mean this shape has three sides so it's a polygon this one has four this one has five polygons can also have 6 7 8 9 10 11 12 12 any number of sides as long as they have at least three is this shape a polygon yes it is a closed figure with three or more straight sides it has three sides so that counts is this shape a polygon yes it's also a closed figure and it has four straight sides so that's three or more four is more than three is this shape a polygon no it doesn't have three or more straight sides is this shape a polygon yes it is a closed figure with three or more in this case six straight sides is this shape a polygon no it's not a closed figure it's open on one side is this shape a polygon no this heart shape is not a polygon because it doesn't have three or more straight sides its sides are rounded is this shape a polygon yes this star shape is a closed figure with three or more straight sides it's a polygon polygons are classified or named by the number of sides they have these are triangles triangles are polygons that have exactly three sides these are quadrilaterals quadrilaterals are polygons with four sides a five-sided polygon is called a pentagon a six-sided polygon is a hexagon if it has seven sides it's called a hectagon eight sides is an octagon a nine-sided polygon is called a nonagon hens sides is a decagon polygons can be regular or irregular this is a regular hexagon this is an irregular hexagon regular polygons have congruent or equal sides and angles all of the sides of this regular hexagon are the same length and all of the angles have the same degree measurement irregular polygons do not these sides are all different lengths and the angles are all different too let's look at some examples of regular polygons and irregular polygons here is a regular triangle all of its sides sides and angles are congruent here's an irregular triangle the bottom of this triangle is longer than the sides and the angles are different too here's a regular quadrilateral a square it has congruent sides and congruent angles this rectangle is irregular because some of its sides are longer than others this is a regular pentagon and this is an irregular Pentagon here's a regular hexagon compared to an irregular hexagon looks kind of stretched out and a regular octagon compared to an irregular [Music] octagon here's a regular quadrilateral and here are some irregular quadrilaterals like a trapezoid a parallelogram and a rectangle because they don't have congruent sides and angles here's a regular pentagon and here are some irregular pentagons it might still look like a regular pentagon just stretched out or it might look totally different as long as it still has five straight sides it's an irregular Pentagon here's a hexagon and here are some irregular hexagons let's compare a regular hectagon with seven sides to some irregular heptagons regular OCT compared to irregular octagons regular nonagon compared to some irregular nonagons a regular decagon compared to irregular decagons let's review polygons polygons are closed shapes with three or more straight sides there are many different types of polygons just like there are many different types of dog dogs regular polygons have congruent or equal sides and angles and irregular polygons do not polygons are named by the number of sides they have if it has three sides it's a triangle four sides is a quadrilateral five sides is a pentagon six sides is a hexagon seven sides is a hectagon eight sides is a octagon nine sides is a nonagon and 10 sides is a decagon this video was created by La Fontaine of knowledge click the link in the description for lesson materials that go along with the video and subscribe to my channel for more videos like this